Zinc Oxide Content Research Articles

Experimental Investigation on Thermal Conductivity of Palm Oil and Zinc Oxide PFAE-based Nanofluids

Vegetable oil (VO) have been constantly researched as an alternative to the conventional mineral oil (MO) in the application of transformer insulation liquid. VO is deemed as a suitable replacement for MO as they are a renewable source, cheaper in price, and have a high thermal conductivity, high flashpoint, and high breakdown voltage value. In addition, the trending interest in nanofluids has made it possible to further improved the insulating properties of VOs. This paper reports the experimental results of thermal conductivity test of Palm oil-based nanofluids and Palm fatty acid ester (PFAE)-based nanofluids. The nanoparticles used in this work is Zinc Oxide (ZnO) <50nm nano powder and the nanofluid (NF) samples are varied by low, medium and high concentrations. The test was conducted at 9 different temperatures from 25°C to 65°C with 5°C gap. The result shows that a low and medium concentration nanofluid has an improvement in thermal conductivity value, up to 42.6% and 59.5% respectively for palm oil-based nanofluid. Meanwhile, the high concentration palm oil-based nanofluid has lower enhancement in thermal conductivity value at certain temperatures. As for PFAE-based nanofluids, the thermal conductivity value has improved by up to 27% and 14.4% for medium and high concentration respectively. Nanofluids with medium concentration of ZnO, has the highest enhancement in insulating and cooling properties for both palm oil and PFAE-based nanofluids. This observation is supported by the kinematic viscosity value of the mentioned nanofluid.

Characteristics of Edible Film from Corn Starch (Zea mays L.) with Additional Glycerol and Variations of Zinc Oxide (ZnO) Nanoparticles

Plastic is one of the most widely used packaging materials. Plastic is made of chemicals that are highly toxic, and its use has produced a lot of waste that is bad for the environment and difficult to decompose. The global community is becoming more and more aware of the value of high-quality food, particularly when it comes to packaging that is safe for human health and the environment. Edible films can be used as an eco-friendly alternative to plastic food packaging options. As a material for packaging, edible film made of biopolymers has been created. This material can be made from biodegradable components and has qualities akin to those of ordinary plastics. When combined with zinc oxide (ZnO), a piezoelectric ceramic with anti-microbial properties, edible film degrades and decomposes readily. This study sets out to identify the effects of variations in zinc oxide nanoparticle concentration properties of edible films made from corn starch (Zea mays L.) and to establish the optimal zinc oxide nanoparticle concentration. ZnO concentrations ranging from 0% to 3% to 9% to 12% were used. The outcomes demonstrated that a concentration of 12% provided the optimal treatment for the properties of edible film. With the addition of 12% ZnO concentration, the edible film's properties improved the most in this investigation, showing 81.94% water resistance, 1.434 MPa tensile strength, and 38.46% elongation percent. The lowest biodegradability value was found in edible film with a concentration of ZnO 12%, within 14 days. The resistivity, tensile strength, and % elongation of the edible film increase with increasing ZnO content.

Adverse Responses following Exposure to Subtoxic Concentrations of Zinc Oxide and Nickle Oxide Nanoparticles in the Raw 264.7 Cells.

The incorporation of engineered nanomaterials (ENMs) in biomedical and consumer products has been growing, leading to increased human exposure. Previous research was largely focused on studying direct ENM toxicity in unrealistic high-exposure settings. This could result in overlooking potential adverse responses at low and subtoxic exposure levels. This study investigated adverse cellular outcomes to subtoxic concentrations of zinc oxide (ZnONPs) or nickel oxide (NiONPs) nanoparticles in the Raw 264.7 cells, a macrophage-like cell model. Exposure to both nanoparticles resulted in a concentration-dependent reduction of cell viability. A subtoxic concentration of 6.25 µg/mL (i.e., no observed adverse effect level) was used in subsequent experiments. Exposure to both nanoparticles at subtoxic levels induced reactive oxygen species generation. Cellular internalization data demonstrated significant uptake of NiONPs, while there was minimal uptake of ZnONPs, suggesting a membrane-driven interaction. Although subtoxic exposure to both nanoparticles was not associated with cell activation (based on the expression of MHC-II and CD86 surface markers), it resulted in the modulation of the lipopolysaccharide-induced inflammatory response (TNFα and IL6), and cells exposed to ZnONPs had reduced cell phagocytic capacity. Furthermore, subtoxic exposure to the nanoparticles distinctly altered the levels of several cellular metabolites involved in cell bioenergetics. These findings suggest that exposure to ENMs at subtoxic levels may not be devoid of adverse health outcomes. This emphasizes the importance of establishing sensitive endpoints of exposure and toxicity beyond conventional toxicological testing.

Effect of green synthesized zinc oxide nanoadditives and rice bran oil biodiesel blend on performance and combustion characteristics of a variable compression ratio diesel engine: an experimental study

AbstractThe aim of this research was to investigate experimentally the performance and combustion characteristics of a four‐stroke, single‐cylinder, water‐cooled variable compression ratio diesel engine using rice bran oil biodiesel blends with zinc oxide nanoparticles. Rice bran oil biodiesel was prepared using a transesterification reaction with a 6:1 methanol‐oil molar ratio and 1% w/w potassium hydroxide as catalyst. Zinc oxide nanoparticles were synthesized using a green method incorporating Psidium guajava leaf extract as a capping agent to reduce precursor use and to reduce the toxicity of the nanomaterial. The synthesized zinc oxide nanoparticles were characterized by using X‐ray diffraction and Fourier‐transform infrared spectroscopy to confirm the formation of highly crystalline pure zinc oxide nanoparticles with a hexagonal wurtzite crystal structure with an average diameter of 20.963 nm. Rice bran‐oil biodiesel‐diesel blend was prepared by volumetrically mixing 20% biodiesel and 80% mineral diesel and was considered as a base fuel for comparison. Zinc oxide nanoparticles were diffused in the base fuel at dosage levels of 25, 50, and 75 ppm, with the aid of ultrasonication. Measurement of the major physicochemical properties of test fuels showed an increase in the cetane number and calorific value and a reduction in viscosity with an increase in the zinc oxide concentration. The overall properties of all the test fuels were found to be similar in comparison with commercial diesel. An experimental engine test was carried out under different loading conditions with a constant speed of 1500 RPM and two different compression ratios – that is, 17.5:1 and 15:1. Among all the test fuels at both compression ratios, engine performance and combustion properties improved with an increase in the zinc oxide concentration. Test fuel with 75 ppm of zinc oxide additive at 17.5 compression ratio resulted in an overall improvement at full load: brake thermal efficiency increased by 2.45%, brake specific fuel consumption reduced by 5.45%, cylinder peak pressure increased by 3.27% and net heat release increased by 10.32% in comparison with base fuel.

Sintering behavior and physical properties of ZnO‐modified BaZrO3 ceramics

AbstractBarium zirconate (BaZrO3) ceramics possesses poor sintering properties, in order to improve its densification behavior and reduce the sintering temperature, zinc oxide (ZnO) was selected as a sintering aid in this study. The effects of ZnO content on the sintering kinetic parameters and physical properties of BaZrO3 ceramic samples heated at 1300–1600°C were investigated. As the addition of ZnO increased from 0 to 5 wt.%, the calculated sintering activation energy decreased from 117.3 to 19.22 kJ/mol. The change of activation energy leads to the decrease of the optimum adding amount of ZnO with the increase of heat treatment temperature, showing 1300°C (5 wt.%), 1400°C (3 wt.%), 1500°C (2 wt.%), 1600°C (1 wt.%). The 1500°C sintered sample with 2 wt.% ZnO achieved a relative density of 96.00% and a maximum cold modulus of rupture (CMOR) of 94.5 MPa.

Conjunctive and concentration dependent effects of nanoscale zinc and boron on the physiological, biochemical, nutrient uptake, and translocation processes in peanut (Arachis hypogaea L.)

In the present investigation, different concentrations (150, 200, 300, 400, and 500 mg/L) of nanoscale zinc oxide (ZnO) and boron (B) were applied through foliar spray (pot culture) to evaluate their effects on the growth and biochemical parameters of peanut. Nanoscale zinc oxide and nano boron were prepared using modified oxalate decomposition and encapsulation methods, respectively, and were characterized using techniques such as, X-ray diffraction (XRD), dynamic light scattering (DLS), ultraviolet–visible (UV–vis) spectroscopy, and transmission electron microscopy (TEM). The average size (37.2 nm, 53.6 nm) and zeta potential (−37.7 mV, −28.3 mV) of nano ZnO and nano boron were measured, respectively. Fourier transform infrared spectroscopic (FT-IR) studies revealed the functional groups that are present in the hydrosols. Highest germination percentage (98.7% and 96%), seedling vigor index (2359 and 1325) and total chlorophyll content (3.28 and 2.24 mg g−1) were recorded at 500 mg/L of nano zinc oxide and nano boron. Significantly higher peroxidase, catalase, superoxide dismutase (SOD) enzymatic activities, pod yield (39.76 g pot−1 and 38.14 g pot−1) and haulm yield (49.56 g pot−1 and 47.05 g pot−1) were also recorded with the application of nano ZnO and boron @ 500 mg/L. Translocation of nanoscale nutrients through stomata was clearly observed. Significant nutrient uptake with the foliar application of nanoscale nutrients has been recorded. The performance of groundnut (in terms of yield, quality and nutrient uptake) was significantly enhanced with the application of nanoscale nutrients and this point to achieving the nutrient bio-fortification with the desired levels for the betterment of human health.

Influence of active, nano, and functionalized zinc oxide particles on the mechanical, cytotoxicity, and thermal stability of carbon black filled SBR/NR blends

AbstractThis study examines the viability of functionalized, nano, and active zinc oxide (ZnO) as an alternative activator in styrene butadiene rubber–natural rubber (SBR–NR) blends filled with carbon black. Concerns about the environmental impact and toxicity of Zn leaching into aquatic organisms necessitate reducing the amount of ZnO in rubber compounding. The mechanical properties, crosslink density, and thermal and morphological qualities of the SBR/NR blends made with these ZnO (F2BB, N2BB, and A2BB) were studied and compared to conventional ZnO loaded blend (C5BB). Thermal stability was evaluated using thermogravimetric analysis and temperature scanning stress relaxation. A2BB showed the highest thermal stability, while F2BB exhibited a 35% increase in tensile strength and a 28% increase in elongation at break due to polysulfide linkages. N2BB and A2BB increased tensile strength by 28 and 16% compared to C5BB. Cytotoxicity of various ZnO concentrations on HT‐22 hippocampal cells was investigated, and active and nano ZnO were found to be less toxic. Using active and nano ZnO can improve the mechanical and thermal properties of the blend while reducing environmental toxicity, allowing for a 60% reduction in ZnO concentration in rubber compounds and resulting in cost savings and a sustainable alternative to conventional ZnO.

Effects of PVP surfactant on nanosuspension stability and optical, dielectric, and rheological properties of zinc oxide nanoparticles dispersed alcohols mixture based nanofluids

Nanofluids (NFs) are state-of-the-art engineered promising properties soft materials which found vital applications in thermal management and electrical insulation, and also gaining much attention in the advances of soft optoelectronic and microelectronic device technologies. The longer-time functionality of the NF material depends on particle suspension stability which can be maintained up to some extent with the addition of appropriate surfactants. Here, we report the promising properties of the semiconductor NF (SNF) samples consisting of a highly rich ethylene glycol (EG) mixture with glycerol (Gly) (90/10 vol%) as base fluid, zinc oxide (ZnO) nanosuspension, and poly(vinyl pyrrolidone) (PVP) surfactant. These formulated 90EG + 10Gly/x wt% (ZnO + PVP) SNFs with varying concentrations (x wt%) of ZnO and PVP are characterized by employing ultraviolet-visible (UV–Vis) spectrophotometer (wavelength range 200–800 nm), precision inductance-capacitance-resistance (LCR) meter (frequency range 50 Hz to 1 MHz), and rotational rheometer (shear rate range 13–132 s−1). The UV–Vis absorbance spectra, recorded on the freshly prepared and aged SNF samples, confirmed that the added PVP enhances longer time suspension stability for ZnO nanoparticles in the H-bonded 90EG + 10Gly viscous base fluid, and also promoted the photosensitivity, electronic transition, and radiation blocking performance of these materials. The dielectric spectra revealed a huge contribution of the electrode and interfacial polarization processes to the dielectric permittivity of the SNFs at low frequencies and their dynamics is explored from the intense relaxation peaks observed in the loss angle tangent spectra. The higher experimental frequency range dielectric permittivity remains frequency independent and it is marginally affected by the ZnO and PVP concentrations in these SNFs, at 298.15 K. The electric modulus and impedance spectra of these SNFs are also provided and analyzed for the charge conductivity and interfacial relaxation processes. The ac electrical conductivity of these materials obeys the power law behaviour along with the dc conductivity part in the range from 5.4 to 6.8 × 10–7 S⋅cm−1. The rheological measurements on these SNFs, in the 303.15 K to 323.15 K, categorized them as Newtonian-type fluids with a considerable increase in dynamic viscosity by PVP dissolution. These materials showed the Arrhenius behaviour of viscous flow having activation energies in the range of 25–27 kJ⋅mol−1. The experimental results of various techniques on these green-formulated SNFs revealed their multifunctionality with great potential for the future generation of soft device technologies, in addition to highlighting their current applications of manageable heat transfer in the flow systems.

Effect of nanodispersed zinc oxide concentrations on the structural, optical, dielectric, viscous, and acoustic properties of ethylene glycol– glycerol mixture based nanofluids

Nanofluids (NFs) are green-formulated innovative soft materials, enormously used for thermal management medium in energy harvesting/ storage and heat transport, as high breakdown voltage insulators/ nanodielectrics in electrical and energy storage systems, and in the advances of soft condensed matter device technologies. In this study, NFs consisting of ethylene glycol (EG) and glycerol (Gly) mixture in equal volumes as the base fluid and semiconductive zinc oxide (ZnO) nanoparticles with increasing concentrations from 0.005 to 1.00 wt% are prepared and characterized by employing different advanced techniques. X-ray diffraction (XRD) patterns recorded directly on these NFs confirmed the homogeneity and nanosuspension stability of ZnO particles in the hydrogen-bonded supramolecular 3D structure of viscous EG–Gly base fluid. The UV-Vis absorbance spectra explained the ZnO concentration tunable photo sensing and UV blocking properties of these semiconductive nanofluids. The 20 Hz to 1 MHz range dielectric spectra revealed high static dielectric permittivity of these NFs, at 298.15 K, confirming them as promising nanodielectric for electric energy storage devices. The dielectric dissipation factor, electric modulus, and impedance spectra confirmed that these EG–Gly/ZnO NFs have electrode polarization and conductivity relaxation processes around 200 Hz and 20 kHz, respectively. The electrical conductivity is observed in the range of 0.32– 0.65 μS/cm with a noticeable increase at the higher ZnO concentration which infers appreciable insulation performance of these NFs. The rheological measurements demonstrated Newtonian behavior of these NFs with a dynamic viscosity of about 69 mPa.s, at 298.15 K. Ultrasound velocity and various acoustic parameters of these NF materials are marginally altered with varying the ZnO concentration and revealed appreciable thermal conductivity of 0.31 W·m–1·K–1, at ambient temperature. The temperature dependent viscosity measurements of EG–Gly/1.00 wt% ZnO sample demonstrated its Arrhenius behavior with high activation energies for both the viscous and relaxation processes. These experimental results establish the EG–Gly/ZnO nanofluids as multifunctional materials for highlighting current applications and also in futuristic soft condensed matter technologies.

PVA Nanofibers Embedded with Different Concentration of ZnO Prepared by Electrospinning Method

Polyvinyl alcohol (PVA) nanofibers were fabricated using the electrospinning method. The nanofibers were embedded with zinc oxide (ZnO) particles by mixing PVA liquid with the ZnO powders during the solution preparation stage. The FESEM images showed an increase in the amount of ZnO particles embedded in the PVA nanofibers as the powder content was increased. Other than that, there are no significant changes in other physical properties of the nanofibers caused by the increasing number of ZnO particle content. This means that ZnO nanopowders (with concentration in the range of 1.63 wt% - 8.14 wt%) can be effectively integrated and embedded into PVA nanofibers without negative consequences on the fibers formation and structure. This will facilitate the fabrication of ZnO embedded PVA nanofibers in some applications that may require it such as drug delivery, filtration, and biomedical application.

Effect of zinc oxide on the mechanical, thermal and physiochemical properties of chitosan-based hybrid membrane for DMFC application

This work uses zinc oxide (ZnO) as a filler to prepare a chitosan-based hybrid membrane. The mechanical, thermal and physiochemical properties of the membranes were studied using different experimental techniques. The water uptake capacity and swelling degree of the composite membranes were increased whereas ion exchange capacity (IEC) decreases with the increase of ZnO content. The ZnO filler reduces the crystalline phase of the hybrid membranes. The hybrid membrane's proton conductivity was measured by EIS experiment and fitted into a comparable circuit model. The ZnO filler improves the membrane's proton conductivity, and the proton transport is controlled by the Grotthus mechanism.

THE CATALYTIC EFFECT OF ZINC-OXIDE (ZNO) ON THE KINETICS OF COMBUSTION REACTIONS OF SOLID WASTE MATERIALS

This study aims to determine the catalytic effect of ZnO on the kinetics of the decomposition reaction of burning solid waste. ZnO catalyst was chosen because it has high mobility and reactivity. samples were prepared and randomly selected consisting of 12 types of inorganic waste and 10 types of organic waste. The research instrument uses (DTA) Differential Thermal Analysis proximate testing. From this test the data in the form of a mass decrease graph will be analyzed descriptively. The description of the data is displayed through the TG-DTG curve and the calculation of the activation energy (Ea) using the fitting model. the DTG curve identifies three peaks indicating the decomposition stages of the three components have different characteristics. The decomposed components are 1. lignocellulosic organic and low stability organic components, 2. Volatile substances from plastic components, 3. hydrocarbon residues and ash reformation. The combustion temperature increases in samples with high catalyst concentrations, but the burnout temperature decreases in samples with high catalyst concentrations. The DTA curve shows the increased reactivity of samples with high catalyst concentrations. Oxidative reactions which are exothermic/external heating increase in samples with high catalyst concentrations. The catalytic effect on the addition of zinc-oxide (ZnO) catalyst concentration to the components showed a decrease in the hydrocarbon component and an increase in the short chain hydrocarbon component. Increasing the concentration of zinc-oxide (ZnO) catalyst in the sample increases the activation energy. However, overall the addition of catalyst concentration in the combustion of organic-inorganic solid waste samples was able to reduce the activation energy at the end of the combustion reaction

Supplementation with Antimicrobial Peptides or a Tannic Acid Can Effectively Replace the Pharmacological Effects of Zinc Oxide in the Early Stages of Weaning Piglets.

Zinc oxide (ZnO) harms the environment and can potentially increase the number of drug-resistant bacteria. Therefore, there is an urgent need to find safe and effective alternatives to improve gut health and reduce the incidence of diarrhea in weaned piglets. This study conducted an antibacterial test of ZnO, antibacterial peptides (AMPs), and tannic acid (TA) in vitro. Thirty piglets were randomly allotted to one of the following three dietary treatments: ZnO (2000 mg/kg ZnO diet), AMPs (700 mg/kg AMPs diet), and TA (1000 mg/kg TA diet). The results showed that the minimum inhibitory concentrations of ZnO and TA against Escherichia coli and Salmonella were lower than those of AMPs, and the minimum inhibitory concentrations of ZnO, AMPs, and TA against Staphylococcus aureus were the same. Compared to ZnO, AMPs increased the digestibility of dry, organic matter and the crude fat. Additionally, TA significantly (p < 0.05) increased the digestibility of dry and organic matter. On experimental day 14, the plasma interleukin-6 (IL-6) content of piglets supplemented with AMPs and TA was increased significantly (p < 0.05). On experimental day 28, alanine aminotransferase activity in the plasma of weaned piglets in the ZnO and TA groups was significantly (p < 0.05) higher than in piglets in the AMPs group. The levels of plasma IL-6 and immunoglobulin M (IgM) were significantly higher (p < 0.05) in the ZnO and AMPs groups than in the TA group. On experimental days 14 and 28, no significant differences were observed in the antioxidant capacity among the three experimental groups. Intestinal microbial diversity analysis showed that the Chao1 and ACE indices of piglets in the AMPs group were significantly higher (p < 0.05) than those in the ZnO and TA groups. At the genus level, the relative abundance of Treponema_2 was higher in the feces of piglets fed a diet supplemented with TA than in those fed diet supplemented with ZnO (p < 0.05). The relative abundance of Lachnospiraceae was higher in the feces of piglets fed a diet supplemented with AMPs than in those fed diet supplemented with ZnO or TA. Overall, AMPs and TA could be added to feed as substitutes for ZnO to reduce diarrhea, improve nutrient digestibility and immunity, and increase the abundance of beneficial intestinal bacteria in weaned piglets.

Study of Edible Film from Corn Starch (Zea Mays L.) on the Quality of Minimally Processed Jackfruit

Minimally processed jackfruits can usually be found in traditional markets, but the fact found that jackfruit is sold unpackaged and the fruit is not fresh, some have even browned and are infested with flies. Refrigerator is usually applied, but this technology is relatively expensive and not all farmers/traders can afford it. Edible film is an alternative that is easily degraded and decomposed by natural composers plus zinc oxide (ZnO) which is a piezoelectric ceramic that has anti-microbial properties. The purpose of this research was to determine the effect of ZnO concentration on the characteristics of edible films and to determine the best concentration of ZnO and its effect on packaging in jackfruit. Variations in the concentration of ZnO used 0%, 3%, 9% and 12%. Observations on jackfruit were carried out at room temperature. Results showed the higher the concentration of ZnO, the better the ability of edible films with ZnO to maintain the quality and shelf life of jackfruit. Edible film with 12% ZnO was able to extend the shelf life of processed jackfruit for at least 5 days at room temperature . Keywords: Hardness, Weight loss, Total dissolved solid, Microbial test, Water content.

Improvement of Optical Properties of Functionalized Polyvinyl Alcohol-Zinc Oxide Hybrid Nanocomposites for Wide UV Optoelectronic Applications

The functionalized polyvinyl alcohol (PVA) based nanocomposites thick films of 80 μm containing 1–3 wt% zinc oxide (ZnO) nanoparticles (NPs) were studied. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy were utilized for studying the structural parameters and formed chemical bonds of the synthesized PVA-ZnO films. In addition, extensive characterization has been done on their linear and nonlinear optical properties. The structural analysis of the PVA-ZnO nanocomposites revealed the formation of a wurtzite hexagonal ZnO phase embedded inside the monoclinic PVA phase. The interaction between Zn–O, and functional groups of the PVA as well as the molecular vibration exhibited in the PVA-ZnO nanocomposites were confirmed by the Raman and FTIR spectroscopy and revealed that the PVA-ZnO is a hybrid nanocomposite. The incorporated ZnO NPs ratios slightly affect the PVA films' structure, meanwhile, exhibited a detectable change in the linear/nonlinear optical properties of PVA. For example, as ZnO concentration increased from 1 wt% to 3 wt%, the direct/indirect optical band gap of PVA slightly decreased from 5.1/4.93 eV to 4.45/4.89 eV, respectively. Other optical characteristics, such as optical conductivity, dielectric constants, absorption coefficient, refractive index, etc., were evaluated. All observed optical properties versus energy/wavelength display a distinct pulse at 1.4 eV/850 nm which corresponds to the difference between the direct and indirect optical band gaps. It is expected that PVA-ZnO hybrid nanocomposites have become appropriate for implementation in numerous electronic applications due to their improved optical characteristics.

Elution and disinfection of silver and zinc nanoparticles in co-fired ceramic water filters

Ceramic water filters (CWFs) are decentralized water treatment technologies commonly used in resource-restricted geographies. Inclusion of silver nanoparticles (AgNP) assists with disinfection but can substantially increase costs. This research investigates AgNP supplementation with zinc oxide (ZnO) as a low-cost bactericide alternative. CWF disks were impregnated with varying AgNP and/or ZnO concentrations and challenged against Escherichia coli. Effluent bacteria were enumerated and monitored over 72 h while eluted metal concentrations were measured and scaled according to surface area to establish ‘pot-equivalent’ estimates (0–50 ppb Ag and 0–1200 ppb Zn). Ag addition correlated to subsequent measured release values, though Zn impregnation did not. Background Zn was thus evidently present. Meanwhile, the eluted metal concentration related to disinfection: a CWF with a pot-equivalent elution estimate of 2 ppb Ag and 156 ppb Zn achieved a Log Removal Value (LRV) of 2.0 after 60 min of filtration and 1.9 after 24 h of storage while a CWF with a pot-equivalent elution estimate of 20 ppb Ag and 376 ppb Zn achieved LRVs of 3.1 and 4.5 after the same filtration and storage times, respectively. Clay elemental composition may therefore impact filter performance more than previously considered This trend was further confirmed by batch experiments with Ag and Zn in concentrations of 0–20 ppb Ag and 0–800 ppb Zn, respectively: bacterial regrowth was only observed when Ag and Zn were each below 5 ppb and 160 ppb while 1 ppb Ag and 800 ppb Zn maintained complete disinfection for 72 h. Increased Zn concentrations thus reduced Ag required to maintain disinfection over time. Overall, it is recommended to include Zn with Ag for CWF to improve short-term and long-term disinfection efficacy and associated water safety.

Zinc Oxide–Incorporated Chitosan–Poly(methacrylic Acid) Polyelectrolyte Complex as a Wound Healing Material

A novel type of porous films based on the ZnO-incorporated chitosan-poly(methacrylic acid) polyelectrolyte complex was developed as a wound healing material. The structure of porous films was established by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and energy dispersive X-ray (EDX) analysis. Scanning electron microscope (SEM) and porosity studies revealed that the pore size and porosity of the developed films increased with the increase in zinc oxide (ZnO) concentration. The porous films with maximum ZnO content exhibited improved water swelling degree (1400%), controlled biodegradation (12%) for 28 days, a porosity of 64%, and a tensile strength of 0.47 MPa. Moreover, these films presented antibacterial activity toward Staphylococcus aureus and Micrococcus sp. due to the existence of ZnO particles. Cytotoxicity studies demonstrated that the developed films had no cytotoxicity against the mouse mesenchymal stem (C3H10T1/2) cell line. These results reveal that ZnO-incorporated chitosan-poly(methacrylic acid) films could be used as an ideal material for wound healing application.

On the toxicity behaviour of composite polyaniline-zinc oxide photocatalytic nanoparticles and their surrogate chemicals

The acute toxic effect of home-made polyaniline-zinc oxide (PANI-ZnO) nanocomposite photocatalyst samples was investigated. Toxicity behaviour was compared with that of their surrogates PANI-emeraldine base (PANI-EB), PANI-emeraldine salt (PANI-ES) and zinc oxide (ZnO). The freshwater crustacean Daphnia magna reacted more sensitively to the exposure than the marine photobacterium Vibrio fischeri and thus higher acute toxicity levels were recorded for Daphnia magna. The toxicity response increased with exposure time for both tested organisms. The hydrophobic PANI-EB was non-toxic, whereas ZnO nanoparticles were toxic towards both test organisms and the main reason of the toxicity of the PANI-ZnO composites. The toxicity behaviour changed with ZnO content rather than the PANI-ZnO nanocomposite synthesis type (in-situ polymerization or hybridization method). The acute toxicity also increased when the PANI-ZnO samples were subjected to UV-A (photocatalytic) treatment (conditions:0.25 g/L catalyst; pH=7.0; t = 180 min; I0 =0.5 W/L). A relationship between the photo-induced Zn(II) release and acute toxicity increase after photocatalytic treatment was evident.

EVA/zinc oxide nanocomposites for active food packaging: selected physical, and microbial properties

The melt-mixing method was used to obtain nanocomposites of ethylene vinyl acetate copolymer (EVA) with 1, 3 or 5wt% of hydrophilic zinc oxide (ZnO) nanoparticles. The contact angle, barrier and antimicrobial properties of the obtained composites were investigated. The nanocomposites were characterized by better hydrophilic and barrier properties, as evidenced by, respectively, a smaller contact angle and lower water vapor permeability and water absorption compared to EVA, which can be explained by the formation of hydrogen bonds between EVA and ZnO. In addition, the composites were characterized by greater bactericidal activity against E. coli and S. aureus. The optimal physical and microbial properties were obtained with 3 wt% ZnO content.

The impact of metallic nanoparticles on gut fermentation processes: An integrated metabolomics and metagenomics approach following an in vitro digestion and fecal fermentation model

Metallic nanoparticles (MNPs) are becoming widespread environmental contaminants. They are currently added to several food preparations and cause a fast-growing concern for human health. The present work aims to assess the impact of zinc oxide (ZnO), titanium dioxide (TiO2), and silver (Ag) nanoparticles (NPs) on the human gut metabolome and microbiome. Water samples spiked with two different concentrations of each MNPs were subjected to in-vitro gastrointestinal digestion and in-vitro large intestine fermentation. The effects of the treatments were determined through 16 S amplicon sequencing and untargeted metabolomics. Multi-omics data integration was then applied to correlate the two datasets. MNPs treatments modulated the microbial genera Bifidobacterium, Sutterella, Escherichia and Bacteroides. The treatments, especially the lower concentrations of Ag and ZnO, caused modulation of indole derivatives, peptides, and metabolites related to protein metabolism in the large intestine. Notably, these metabolites are implicated in ulcerative colitis and inflammatory bowel disease. TiO2 NPs treatment in all concentrations increased E.coli relative abundance and decreased the abundance of B. longum. Moreover, for TiO2, an enrichment in proinflammatory lipid mediators of arachidonic acid metabolites, such as prostaglandin E2 and leukotrienes B4, was detected. For all metals except TiO2, low NP concentrations promoted differentiated profiles, thus suggesting that MNPs aggregation can limit adverse effects on living cells.